Note: Wear gloves to prevent saffron from staining hands.)
Place saffron in a shallow bowl and pour boiling water over; set aside for 5 minutes.
Add grated onion and stir.
Place the chicken breasts in the bowl and turn to coat with marinade.
Cover and place in refrigerator overnight, turning at least once.
To cook, place on a hot coal or gas grill and bar-b-que until chicken is done.
* Percent Daily Values are based on a 2,000 calorie diet. Your daily value may be higher or lower depending on your calorie needs.